why isnt this lower bound?
k = 4; f(x) = 2x^3 - 2x^2 - 3x - 5

Question

why isnt this lower bound?
k = 4; f(x) = 2x^3 - 2x^2 - 3x - 5

tkhunny · Answer

??  Cubic polynomial.  Infinite in both directions and must have one real root.  What lower bound were you finding?  It may have local minima or maxima, but no global.

anonymous · Answer

Well the question just ask to divide synthetically and see if its a low or higher bound and I did the work and got lower bound but I was wrong.

tkhunny · Answer

I see. You should say that you are searching for roots via synthetic division.  Take a good look at what you originally posted.  No such indication.

4 appears to be an UPPER bound.  Why would it also be a lower bound?

Please state the criteria for a Lower Bound.  What pattern is required?

anonymous · Answer

If c < 0 and the numbers in the last row are alternately positive and negative (zeros count as positive or negative), c is a lower bound for the real zeros of f. Lower bounds must be negative.

anonymous · Answer

sorry nm i got it.